Constant-on-time, COT, switching converters present a number of advantages over other types of switching converters. In particular such converters offer a fast transient response, a high efficiency under light load and a smooth transition from continuous conduction-mode CCM to discontinuous conduction-mode DCM of operation.
However, when changing between a high load condition and a low load condition, the switching frequency of the COT converter varies. This is because the on and off switching cycle of a COT converter is controlled based on the load demand instead of an internal pre-determined clock. In addition, COT converters tend to suffer from large output voltage variations.